Q&A with the SLT Development Team

[WaltKnapp]

This is incorrect. Light is only being diverted for the Phase Detect AF which can operate in considerable less brightness than in previous pellicle cameras where viewfinder relied on the the pellicle mirror.

I always assumed that the angle chosen was to move the imaging on the AF unit forward and slightly down. To make room for the EVF unit and make the top profile of the camera a little smaller. I don't think flipping the mirror was even considered, or was rejected early on.

I doubt the change in angle made a lot of difference to the light reflection ratio. And in any case the mirror coating could adjust that.

Walt

[agorabasta]

Walt, they also might have needed to keep the angle away from Brewster... Or they might need a certain angle to have the whole mirror play somehow with polarisation from dielectric reflections... And that in turn depends on the properties of coatings... Et cetera...

They just don't tell it all.

[BrianSmith]

This is incorrect. Light is only being diverted for the Phase Detect AF which can operate in considerable less brightness than in previous pellicle cameras where viewfinder relied on the the pellicle mirror.

I always assumed that the angle chosen was to move the imaging on the AF unit forward and slightly down. To make room for the EVF unit and make the top profile of the camera a little smaller. I don't think flipping the mirror was even considered, or was rejected early on.

I doubt the change in angle made a lot of difference to the light reflection ratio. And in any case the mirror coating could adjust that.

Walt

Barry made the statement that "Sony obviously made the mirror oversized to try to get more light in there and up to the AF system" which is incorrect.

It's not the size (or the angle) of the mirror that affect how much light is reflected. You are correct when you say it's the coating.

There were a number of factors that went into mirror angle including minimizing body depth - which would be less of a factor in larger bodies.

The pellicle designs allows continuous Phase Detect AF which would not be possible with a constantly flipping mirror. The mirror was intended to flip up to provide access to clean the sensor.

[BrianSmith]

Fast CDAF requires different lens motors. The E-series lenses have these motors. I can't explain how it work in detail, but you have to imagine a system which oscillates focus over a diminishing cycle to determine the correct point. Pentax do a massive cycle - it is like watching a firework display to see the K-5 focus. Sony is visib;e, and can create a strange vibrating image preview. Panasonic - used one, forget it! Just forget it. It's a joke.

David

David is absolutely correct. The one additional factor I would mention is the weight of the moving elements which are pretty light and small in the E-series lenses.

[David Kilpatrick]

Sorry about my post-photokina sloppy typing and loads of typos. CDAD = meant CDAF.

David

[catalytic]

Fast CDAD requires different lens motors. The E-series lenses have these motors. I can't explain how it work in detail, but you have to imagine a system which oscillates focus over a diminishing cycle to determine the correct point.

Yes, i understand the CDAF "contrast peaking" back and forth approach, and i don't doubt that the E-series lenses have motors intended for CDAF use, but the problem is that despite the lens-specific optimizations (including light focusing groups), the NEX CDAF is noticeably slower than Panasonic's.

Panasonic - used one, forget it! Just forget it. It's a joke.

Used which model? Can you elaborate on how it's a joke? The G-series CDAF is universally praised as being the best in the industry, and the GH2 took it to the next level. I have a G1 myself, and the AF is easily much better than the PEN E-P1. It's not just about the speed, either. The selectivity of the focus point and the reliability in terms of target selection and low-light focus is much better on the G1, whereas the E-P1 would often focus on the background instead of the subject, and hunt and struggle in low light. Trying the NEX at the store (wanted something with the CDAF performance of the G1, but with a better sensor), it was disappointingly more like the PEN than the G1 when it came to CDAF, and the GH2 is apparently twice as fast as its predecessors.

[David Kilpatrick]

Not able to get hold of a GH2, only a G2. With 14-42mm lens. Honestly, I would never buy it. The lens is poor, with a degree of softening to the outer field I've never seen from a Sony/Minolta lens, and focusing was erratic. Apart from that, even the best the 12 megapixel sensor delivered was not really all that sharp. I have used the EP-1, and found much the same thing. The results reminded me a very good consumer camera, a step above the KM A2 for example, but not a match for a 'proper' 12 megapixels like the Nikon D5000 or indeed the Sony A700 - and even less a match for any of the Sony APS-C 14 megapixel sensors.

The NEX CDAF may not be quite a 'fast' to a lock as the Panasonic, but it's very accurate. I would not use any of them for following focus. The G2 results were so disappointing we had to check the lens stabilisation was working, which it was. I am just used to never having to think hard about sharpness at all, whether from lens quality, focusing or hand-held shot stabilisation with the NEX.

David

[David Kilpatrick]

I should point out that I did set up the G2 carefully for raw shooting as required, and the normal AF-S type mode. But I may not used its optimum focus mode. With the NEX, I do not use multi/wide area - single selectable point. Using the wide area it takes ages to decide what to focus on and often just picks the highest contrast area even if not the subject - as you found with Oly. Small single focus zone only, essential.

David

[bfitzgerald]

The pellicle designs allows continuous Phase Detect AF which would not be possible with a constantly flipping mirror. The mirror was intended to flip up to provide access to clean the sensor.

I would mention I have used a Canon EOS-1D Mark III which is capable of 10fps. Though that model had some criticism regarding performance. Entirely the reverse of what I would use..I prefer smaller lighter bodies myself up to medium size. This beast is far too big and heavy for my needs.
However. I would question the "need" from most shooters for 10fps. I suspect it's not really needed by that many or would even get much use for portrait, landscapes or wedding photographers.I can think of only one occasion where I needed more FPS, and that was in an equestrian event. In any case the light would certainly not allow the use of 10fps (low light)

To this day I still find the Dynax 7 as having an excellent AF system and it really does nail focus and can track moving subjects very well. So I'm unconvinced that translucent brings serious AF advantages over a "good" traditional mirror based system.

For Sony the goal may have been EVF, thus the non moving mirror was part of getting towards that..or high FPS. In the latter I don't think 10fps on it's own will appeal to a broad number of photographers. As for the EVF that's open to debate. I would rate FPS as fairly low down the list of "wants' on any DSLR but that's me and my needs.

[David Kilpatrick]

The 10fps is used for a lot more - HDR, Anti Motion Blur, stitched panoramas, 3D panoramas, 3D 16:9 stills, Twilight Mulitshot - it's not all about action speed stuff

David

[bfitzgerald]

I'm not knocking those features but really we're talking about stuff that might be of limited use to some or not very high up the "want/need" list. I've no problems with 10fps but it comes at a price for some users. And I doubt very much you need 10fps for a panoramic stitch in camera.

3D is still very early days and I'd be a bit cautious as to just how much impact that will have. In the short term probably not very much. I'm still of the view Sony put so much effort into these areas (and sure some are decent HDR looks better than most) yet they can't manage to get a full time ISO display in the viewfinder (I'm talking OVF models here) or make the AEL work switch spot metering, or put P shift on their cameras!

Why?? Their priorities are all wrong. One day they'll run out of gimmicks to add and what happens then? Can we get the basic stuff right then add these bits?

I've just finished reading a Pentax user manual and my mind is blown! I can actually do useful things that I can't on a Sony DSLR! A lot of things some small some, not very useful (or gimmicks) but many that will make life easier.

[David Kilpatrick]

If we didn't have Sony, the Pentax K-5 would be my choice. The viewfinder is just - lovely. Superb matte field, very bright, very sharp. It's the best DSLR I have seen for some time and it is what Sony should have been making to replace the A700.

But what the A55/33 etc have to offer is still equally valuable in its different way.

Also, Sony has been reading your forum posts. And mine, and many others. Paul Genge told me that the comments - adverse and favourable - on forums had produced a complete change of basic attitude at Sony. He said they were no longer the same company, and much of this was a result of reading what users and potential users were saying on-line. 'Listening'. That's what the whole press conference was about; Sony is opening up, understanding better, they've put back many features (some may simply not be possible) and will continue to do more. I can tell - Paul was delighted about this.

David

[mike2008]

If we didn't have Sony, the Pentax K-5 would be my choice. The viewfinder is just - lovely. Superb matte field, very bright, very sharp. It's the best DSLR I have seen for some time and it is what Sony should have been making to replace the A700.

But what the A55/33 etc have to offer is still equally valuable in its different way.

Also, Sony has been reading your forum posts. And mine, and many others. Paul Genge told me that the comments - adverse and favourable - on forums had produced a complete change of basic attitude at Sony. He said they were no longer the same company, and much of this was a result of reading what users and potential users were saying on-line. 'Listening'. That's what the whole press conference was about; Sony is opening up, understanding better, they've put back many features (some may simply not be possible) and will continue to do more. I can tell - Paul was delighted about this.

David

That's good news. Makes it even odder though that there are still issues with the A33 in the studio (EVF shows what exposure it think it will see at the given shuter speed and f/number, but you're using a flash so it's far too dark), but worse now as the EVF goes dark instead of the LV on the LCD, so there is no way of seeing anything. You had an update on this a while ago, do you think they are still aware of the problem?

[bossel]

... had produced a complete change of basic attitude at Sony. He said they were no longer the same company, and much of this was a result of reading what users and potential users were saying on-line...

That's good to hear - and that's what convinced me to fork out some cash for my NEX5. I was interested in it from the beginning, but hesitating (user-interface!). The news from Photokina won me over. They could have made a better UI just for the next camera, but 'upgrading' the current models to be more configurable is a good sign.

[catalytic]

Not able to get hold of a GH2, only a G2. With 14-42mm lens. Honestly, I would never buy it. The lens is poor, with a degree of softening to the outer field I've never seen from a Sony/Minolta lens, and focusing was erratic. Apart from that, even the best the 12 megapixel sensor delivered was not really all that sharp.
[...]
The NEX CDAF may not be quite a 'fast' to a lock as the Panasonic, but it's very accurate. I would not use any of them for following focus. The G2 results were so disappointing we had to check the lens stabilisation was working, which it was. I am just used to never having to think hard about sharpness at all, whether from lens quality, focusing or hand-held shot stabilisation with the NEX.

Ah, that explains it... No, i'm not surprised that you were disappointed with the results, especially from the 14-42 lens. Surprisingly, I found the original 14-45 kit lens to be disappointing from personal experience as well (surprising because it got good test results from all the lens tests over the Net). What i've found from my 14-45 was that when the OIS stepped in to prevent motion blur, it often made it worse. Over time, i have observed many a shot that was ruined by the erratic behaviour of the image stabilizer. I suspect that's what you're seeing here.

Furthermore, the 14-42 lens has been "detuned", or rather, cheapened from the original 14-45 kit lens to allow Panasonic to maintain profit margins while they cut costs to compete with Sony, Samsung, Olympus, et al. Initial tests of the 14-42 indicate that the corner performance was not as good as the original 14-45, despite the fact that the optical design was not supposed to have changed. Sadly, the evidence thus far suggests that Panasonic did cut costs across the board for the 14-42 -- not just substituting a plastic mount for a metal one and removing the OIS ON/OFF switch. Although, i don't know how they could have saved money with the optics, as the new lens uses the same number of elements in the same configuration...

In any event, the G1 and PEN sensors are sharp and high resolution. I am certain that the sensor is not at fault here, having seen every test on the Net showing top resolution scores that approach Nyquist, and my own testing indicates much the same. Here are a couple sample pics from my G1... the first using a Nikon 180mm lens, and the second two using the 14-45 kit lens. I think the resolution is competitive with any 12 mp sensor.

http://catalytic.ca/G1_samples/